High temperature cobalt-base and nickel-base superalloys are used in the manufacture of high temperature operating gas turbine engine components, including combustors and turbine vanes and blades. During the operation of such components under strenuous high temperature conditions, various types of damage or deterioration can occur. For example, cracks can result from thermal cycling and foreign object impact. In addition, such components can experience damage, such as cracks and inclusions during manufacture. Because the cost of components formed from high temperature cobalt and nickel-base superalloys is relatively high, it is typically more desirable to repair these components than to replace them.
Repair methods for components formed from superalloys have included vacuum brazing techniques with alloy powders or mixtures of powders, such as those described in U.S. Pat. No. 3,759,692 to Zelahy, U.S. Pat. No. 4,381,944 to Smith, Jr. et al, and U.S. Pat. No. 4,478,638 to Smith, Jr. et al. With the advent of higher strength and more highly alloyed superalloys, improved repair materials have been required, such as that taught by U.S. Pat. No. 4,830,934 to Ferrigno et al., assigned to the assignee of the present invention. Ferrigno et al. teach the use of an alloy powder mixture of equiaxed particles that results in a repair material characterized by high strength and a unique microstructure that is closely matched with the microstructure of the article being repaired.
While the repair material taught by Ferrigno et al. performs well with many high strength cobalt-base and nickel-base superalloys, further advancements in these types of alloys have resulted in the requirement for improved repair materials, particularly for the repair of single crystal (SX) and directionally solidified (DS) gas turbine engine components.